Pneumatic tool.



H. s. HUNTER. PNEUMATIC TOOL. APPLICATION FILED BEPT.1H, 1913. I

Patented July 7, 1914.

WITNESSES HARRY S. HUNTER, OF PITTSBURGH, PENNSYLVANIA.

PNEUMATIC TOOL.

Specification of Letters Patent.

rammed July 7, 1914.

Application filed September 18, 1913. Serial 110,790,418.

To all whom it may concern:

Be it known that I, HARRY S. HUNTER, a citizen of the United States, andresident of Pittsburgh, in the county of Allegheny and State ofPennsylvania, have invented certain new and useful Improvements inPneumatic Tools, of which the following isa spceification.

The primary object of this invention is to provide simple andeiiicientmeans for automatically locking the tool piston against movement withinthe cylinder when the tool is not in working position, thereby renderingit impossible for the piston to pulsate when the rivet set or other toolis not in en gagcmcnt with the work.

It is not an uncommon occurrence to have the throttle valve of apneumatic tool opened prematurely, either by accident or through error,causing the piston to deliver one or more blows to the rivet set orother tool before the latter is in position to transmit the blows to thework. In those types of tools wherein the movement of the rivet set isnot restricted, premature piston strokes cause the set or other tool tobe projected from the cylinder with much violence, endangering personsand property in its path. In those forms of tools in which free movementof the rivet set is restricted, or in which the set is held againstmovement when the tool is not in operative position, the force of thepremature piston blow is transmittcd'to the tool cylinder and is liableto injure the latter or the confined set, or the means for confining theset. With the present invention these ditlieulties are overcome byproviding a lock for automatically engaging and securing the piston inrearward position whenever the tool is out of operative engagement withthe work.

In the accompanying drawings, Figure 1 is a view of a pneumatic tool ofwell known type, the cylinder thereof being shown in section toillustrate the locking means in nor mal or piston-locking position. Fig.9. is a longitudinal section of the lock mechanism on a larger scalethan in Fig. 1, the lock being shown retracted as when the tool is inuse. Fig. 3 isa cross-section of the lock mechanism and a portion of thecylinder, taken on line 3-3 of Fig. 1.

Referring to the drawings, 2 designates the cylinder of a pneumatic toolof conventional form, 3 being the upper or outer portion of the toolbody containing the valve mechanism, 4 the hand grip, and 5 the fingerpiece of the throttle valve. As the invention is not concerned with thevalve mechanism, valve ports, etc, the tool body and hand grip aresimply shown in outline.

6 is-the piston operative in cylinder 2 which, in the embodiment hereshown, is

' adapted to deliver blows to the shank portion 7 of the rivet set 7,tlielatter being movably held at the outer end of the cylinder by theusual spring clip 8. While the tool here shown is a' rivet set,-it willbe understood that the invention is not restricted thereto, beingadapted to be utilized in connection with any other tool to which blowsmay be imparted by the piston.

The wall of cylinder 2 is formed with the through opening 5), andmovable therein is the latchdike bolt 10 which is adapted to beprojected into the cylinder, as in Fig. 1, by spring 11 confined againstthe outer end of the bolt by the cap nut 12. The location of the bolt ispre t'erably such as to engage the outer extremity of the piston whenthe latter is fully retracted, as in Fig. 1, the inner end of the boltbeing beveled at 10 to pass the piston on the backward stroke of thelatter and automatically lock it at the completion of such stroke.

Tntersecting the bolt cavity is a longitudinal recess 13 in cylinder 2from which extends rod passage 14 to the forward end of the cylinder,and slidable in cavity 13 is the bolt -retracting stem 15 which extendsthrough slot 16 in bolt 10. A spring 17 confined in the cavity behindthe headed end of stem 15 holds the latter normally projected toward theforward end of the cylinder, as in Fig. 1, its position then being suchas not to interfere with the piston-locking action of the bolt.

Stem 15 is formed with enlargement 18 having one end beveled at 18, sothat when the stem is retracted against the. pressure of spring 17 thewedging face of the enlargement, operating in bolt slot 6, retracts thebolt out of piston-engaging position, as in Fig. 2, the bolt being thusheld until stem 15 is permitted to move under the pressure of spring 17,whereupon the bolt 1s again projected into locking position by spring11. The bolt-rctracth1g stem 15 is actuated by rod 19 movable in the rodcavity 14, the rod projecting through the forward extremity of thecylinder and engaging the usual external shoulder 20 of the tool 7 saidshoulportion.

Operation: Spring 17 being stouter than spring 11, stem 15, red 19, andthe tool are held normally in forwardly projected position, as in Fig.1, with the bolt in engagement with the extremity of the piston. This isthe position of the parts when the tool is.

not in actual use, as between riveting oper ations, etc. Hence, eventhough the throttle is opened accidentally or prematurely, it isimpossible for the piston to pulsate, so that no portion of the tool. issubjected to shock or jar. As soon, however, as thetool as a whole ispresented to and pressed against the work, the forward movement of thecylinder relatively to. the rivet set or other tool 7 causes achrresponding movement of the cylinder relatively to the rod 19, therebyretracting the bolt by forcing it over the wedging face of enlargement18 and contracting spring 17, as in Fig. 2, and with the tool thus inworking position the pistonis free to pulsate when the throttle isopened. But the instant the tool is removed from the work, or theforward pressure by the operator incident to holding the tool isrelaxed, spring 17 forces stem 15, rod 19, and the rivet set intoforward position and releases the bolt, so that it is m readiness tolock the piston at the completion of the next backward stroke.

It will be understood that while I have illustrated and described adesirable and preferred adaptation of the invention; it

may be variously embodied in pneumatic percussion tools of difierentkinds, and for performing a variety of work, without departing from thespirit of the appended claims.

I claim 1. The combination with the cylinder and blow-imparting,pistonvof a portable pneumatic tool, of a lock device carried by the tool forholding the piston inoperative, and

means actuated by pressure of the tool ing the lock.

3. In a pneumatic tool, the combination of a cylinder, a blow-impartingpiston movable therein, a lock device adapted to hold the pistoninoprative,1and lock-actuating means adapted to be operated by pressureon. the cylinder toward the work for moving the lock out ofpiston-holding position.

- 4. llln a pneumatic tool,'t l1e combination of a cylinder, ablow-imparting piston movable therein, a bolt adapted to project intoposition to engage the piston and hold it inoperative, and a backwardlymovable boltoperating device normally projecting beyond the forwardextremity of the cylinder and adapted to be moved rcarwardly by pressureof the cylinder toward the work and operate the bolt.

5. lln a pneumatic tool, the combination of a cylinder, ablow-impartingpiston movable therein, a movable device carried by the tool and adaptedto. bemoved by pressure of the tool toward the work, a piston lock, andan operative connection between said movable device and the lock.

6. In a pneumatic tool, the combination of a cylinder, 21 blow-impartingpiston movable therein, a rod normally projecting beyond the forward endof the cylinder and movable longitudinally of the latter, a piston lock,and an operative eonncction be tween the rod and said lock forretracting the latter under pressure of the cylinder toward the work. i

7. In a pneumatic tool, the combination of a cylinder, a blow-impartingpiston mov able therein, a spring-actuated mitten-engaging bolt confinedin the cylinder wall and normally projected into piston-engagingposition, and a device adapted to be moved longitudinally of thecylinder by pressure of the cylinder toward the work, said device havingwedging engagement with the bolt for retracting the latter.

8. In a pneumatic tool, the combination of a cylinder, a blow-impartingpiston movable therein, a springactuated bolt confined in the cylinderwall and normally projected into piston-engaging posit-ion, abolt-retracting device movable in the cylinder and a spring for holdingsaid device normally extended toward the front end of the cylinder, saiddevice when moved rearwardly adapted to retract the bolt and meansactuated by pressure of the cylinder toward the work for movingrearwardly the bolt-actuating device.

9. ][n a pneumatic tool, the combination of a cylinder, 2.blow-imparting pisten movable therein, a spring-actuated lock confinedin the cylinder wall and movable transversely of the cylinder andnormally projected into piston-engaging position, aboltengaging wedgedeyice ovable longitudinally of the cylinder i nd adapted when movedrearwardly to retract the bolt, a spring for holding said devicenormally in forward osition, and a rod movable longitudinal y of thecylinder and adapted to be moved rearwardly by pressure of the cylindertoward the work and moving rearwardly with it the bolt-operating device.

'10. In a pneumatic tool, the combination lldtlt cylinder for impartingblows to the tool, a piston lock, and a lock-releasing ,device adaptedto be actuated by movement of the cylinder relatively to the tool whenthe latter is pressed against the work.

11. In a pneumatic tool, the combination of a cylinder, a tool movablymounted at the forward end of the cylinder, a piston in the cylinder forimparting blows to the tool, a piston lock, a rod movable longitudinallyof the cylinder and adapted to engage the tool and be moved rearwardlyby movement of the cylinder relatively to the tool when the latter ispressed against thework, an operative connection between the rod andlock for retracting the latter when the rod is moved by the tool, aspring for moving the look into piston-holding position", and a springfor holding the rod normally in forward position.

12. ln'a pneumatic tool, the combination of a cylinder, a blow-impartingpiston movable therein, the cylinder wall formed with intersectinglongitudinal and transverse recesses, a piston lock movable in thetransverse recess, a lock-actuating device movable in the longitudinalrecess and adapted when moved in one direction to permit the lock tomove into piston-holding osition and when moved in a reverse c irectionadapted to retract the lock, and means for operating the lock-actuatingdevice.

13. Inpneumatic tool, the combination of a cylinder, a blow-impartingpiston movable therein, the cylinder formed with intersectinglongitudinal and transverse recesses,

a slotted piston lock movable in the transverse recess, a sprlng formoving the lock into piston-holding )osition, a wedge-shaped devicemovable in tie said longitudinal recess and extending through the lockslot and adapted when in forward position to perinit the lock to moveinto piston-holding position and when moved rearwardlv adapted toretract the lock, aspring for holding the lock-actuating device normallyin forward position, and a rod adapted to be moved rcarwardly bypressure of the cylinder toward the work and thereby actuate said device to retract the lock.

14. In a pneumatic tool, the combination of a cylinder, a blow-impartingpiston movable therein, a lock device movable in the cylinder wall andadapted to hold the piston when the latter is retracted, andlock-actuating means.

15. In a pneumatic tool, the combination of a cylinder, atblow-imparting piston movable therein, a lock device movable in thecvlinder wall and adapted to engage the outer extremity of the plstonwhen the latter is retracted, a tool movably mounted at the forward endof the e linder and adapted to receive blows from t io piston, and alockreleasing device carried by the cylinder and engaging the tool andadapted to be operated to release the lock by forward movement of thecylinder relatively to the tool when the latter is pressed against thework.

In testimony whereof I ailix my signature in presence of two witnesses.

HARRY s. HUNTER.

Witnesses:

J. M. NESBIT, F. E. GAITHER.

